1. Field of the Invention
The present invention relates to an electro-optical device and a projection display device including the same.
2. Description of the Related Art
In general, a liquid crystal panel used in a projection display device, such as a liquid crystal projector, is mounted to the inside of a housing of the projection display device, with the liquid crystal panel being accommodated in a case member formed of, for example, synthetic resin. Usually, a flexible wiring substrate is connected to the liquid crystal panel. With the flexible wiring substrate being connected, the liquid crystal panel is installed and positioned in the case member in order to affix it to the case member with, for example, an adhesive or a holding fixture, after which a mounting hole or the like formed in the case member is positioned at a mounting portion formed inside the projection display device and secured thereto by a method such as screwing.
A liquid crystal panel module used as an electro-optical device including the above-described liquid crystal panel and case member is used as a light valve for forming a predetermined image as a result of receiving light from a light source in the projection display device. The image formed by the liquid crystal panel module is enlarged by a projection optical system of the projection display device, and the enlarged image is projected onto, for example, a screen.
FIG. 1 is an exploded perspective view of a conventional liquid crystal panel module, while FIG. 2 is a schematic view showing in section the general structure of the conventional liquid crystal panel module. The liquid crystal panel module may consist of a liquid crystal panel 10 and a case member 20 for accommodating the liquid crystal panel 10 therein. In order to form the liquid crystal panel 10, an element substrate 11 and an opposing substrate 12, both of which are formed of glass or the like, are placed with a predetermined space formed therebetween in order to bond them together with a sealant 14. After the bonding of the substrates 11 and 12, liquid crystals 10a are injected between the substrates. The case member 20 is formed of, for example, synthetic resin, which is black or any other color possessing light-shielding capability.
In the liquid crystal panel 10, an active element such as a known TFT (thin-film transistor) element, a pixel electrode formed of a transparent electrical conductor such as an ITO (indium tin oxide) conductor, wiring, an alignment layer, etc., are formed on the inside surface of the element substrate 11. A known opposing electrode, an alignment layer, etc., are formed on the inside surface of the opposing substrate 12. Thus, an active matrix type liquid crystal panel structure is formed. A light-shielding layer 12a serving as a frame defining a light-transmissive area (or an effective display area) of the liquid crystal panel 10 is formed at an outer peripheral portion of the inside surface of the opposing substrate 12.
In the projection display device, the liquid crystal panel module is irradiated with gathered and concentrated light, and the light is either transmitted or blocked by a plurality of pixels formed in the effective display area of the liquid crystal panel in order to form a predetermined image. Each pixel is controlled by an electric field applied as a result of an electrical potential difference between the pixel electrode and the opposing electrode. Here, when there are any scratch defects or dust on the outside surface of either the element substrate 11 or the opposing substrate 12 of the liquid crystal panel 10, the scratch defects or dust disturb the image, resulting in the problem that the quality of the projected image is reduced. Since the image formed by the liquid crystal panel 10 is enlarged and projected, this problem is particularly serious, so that the aforementioned scratch defects or dust considerably adversely affect the image.
In order to overcome this problem, a method in which transparent substrates 1 and 2 are adhered to outside surfaces of the element substrate 11 and the opposing substrate 12 of the liquid crystal panel 10, respectively, has, hitherto, been developed. The transparent substrates 1 and 2 are adhered to the element substrate 11 and the opposing substrate 12, respectively, with a transparent adhesive which is not shown. For the transparent adhesive, it is preferable to use a material whose refractive index is approximately equal to those of the element substrate 11 and the opposing substrate 12 and those of the transparent substrates 1 and 2. Examples of the transparent adhesive are silicone adhesive and acrylic adhesive, which are transparent after hardening. Accordingly, by adhering the transparent substrates 1 and 2 to the outside surfaces of the element substrate 11 and opposing substrate 12 using a transparent adhesive, the quality of the image is not affected even if there are any scratch defects on the outside surfaces of the element substrate 11 and the opposing substrate 12, and dust is prevented from sticking onto the outside surfaces of the element substrate 11 and the opposing substrate 12. Although scratch defects may be formed or dust may stick onto the outside surfaces of the transparent substrates 1 and 2, the focus of light radiated from the light source is usually set so as to be situated in the liquid crystal panel 10, so that, due to a defocusing effect, the image quality is virtually unaffected.
The case member 20 includes a hole 20a which extends through the top and bottom thereof so as to accommodate the liquid crystal panel 10. The hole 20a includes open sections 20b and 20c formed at both the front and back sides of the accommodated liquid crystal panel 10. An inwardly protruding edge 21 is formed at an edge of the open section 20c so as to engage the outside surface of the transparent substrate 2 accommodated in the hole 20a. A holding frame 24, which is stopped by an engaging protrusion 23 formed at the outside surface of the case member 20, is mounted at the open section 20b in order to hold the outside surface of the transparent substrate 1 accommodated in the hole 20a. A step 22 is formed at the middle of the hole 20a in accordance with the outside shape of portions of the element substrate 11 protruding outwardly of the opposing substrate 12 of the liquid crystal panel 10.
In assembling the liquid crystal panel module, after adhering the transparent substrates 1 and 2 to the front and back sides of the liquid crystal panel 10, an adhesive whose main component is, for example, silicone rubber is applied to the protruding portions of the element substrate 11 and the inside of the case member 20, and, from the open section 20b in the case member 20, the liquid crystal panel 10 and the transparent substrates 1 and 2 are placed into the case member 20. At this time, in the direction in which the liquid crystal panel 10 and the transparent substrates 1 and 2 are placed (that is, the thickness direction of the panel), the liquid crystal panel 10 and the transparent substrates 1 and 2 are positioned as a result of bringing the outside surface of the transparent substrate 2 and the protruding edge 21 into contact with each other. In the direction of extension of a surface of the liquid crystal panel 10, they are positioned as a result of bringing an end of the opposing substrate 12 and the inside surface defining the hole 20a into contact with each other. Lastly, the holding frame 24 is fitted to the engaging protrusion 23 in order to hold the panel assembly so that it does not get dislodged from the open section 20b, and then the adhesive is allowed to harden in order to form an integral structure.
In a projection display device including the above-described conventional liquid crystal panel module, due to restrictions on the structure of the device or depending on whether or not measures against dust need to be taken or the quality of an image needs to be improved, the liquid crystal panel module may be constructed by adhering either one or neither one of the transparent substrates 1 and 2. However, the above-described case member 20 is constructed so as to position and hold in its interior the panel assembly in which the transparent substrates 1 and 2 are adhered to the liquid crystal panel 10. Therefore, in the case where the transparent substrate 2 is not adhered to the liquid crystal panel 10, the protruding edge 21 can no longer be used as a positioning and holding member, which means that the case member 20 can no longer be used as a positioning and holding member. In addition, light leakage may occur due to the formation of gaps. Therefore, it is necessary to make available a case member every time a differently structured liquid crystal panel module is used. Further, for example, the shape of the case member is changed depending on whether or not the structure of a panel assembly includes a transparent substrate, making it necessary to form the mounting section disposed in the projection display device in correspondence with the shape of the case member. This results in the problems of increased manufacturing costs and complicated product control.
The conventional case member 20 is constructed so as to hold the outside surface of the transparent substrate 2 in the thickness direction thereof by the protruding edge 21 formed at the open section 20c, causing the case member 20 to be thicker than the panel assembly, resulting in the problem that a large space is required to place the liquid crystal panel module in the projection display device.
In the projection display device, overheating tends to occur because the liquid crystal panel module is irradiated with intense light from the light source, making it necessary to efficiently cool the liquid crystal panel module in order to prevent malfunctioning thereof caused by the liquid crystals getting hotter. However, in the liquid crystal panel module made thick by adhering the transparent substrates 1 and 2 and forming the protruding edge 21 on the case member 20, it is difficult to increase heat-dissipation efficiency, so that the strength of a cooling fan used to forcingly cool the liquid crystal panel module needs to be large, making it difficult to reduce noise during operation.
In order to overcome the above-described problems, it is an object of the present invention to provide an electro-optical device comprising an electro-optical panel accommodated in a case member, wherein, by forming the case member so that it has a different structure, the case member does not need to be changed depending on whether or not a transparent substrate is bonded in the structure of the panel, the case member can be made thinner than the conventional case member, and the heat-dissipation capability is increased.
According to the present invention, there is provided an electro-optical device which may consist of:
an electro-optical panel including an opposing substrate and an element substrate having a larger area than the opposing substrate; and
a case member including an open section at the opposing substrate side and another open section at the element substrate side, the case member accommodating the electro-optical panel from the open section at the element substrate,
wherein, between the open section at the opposing substrate side and the open section at the element substrate side, the case member includes a positioning section which accommodates the opposing substrate and contacts an edge of the element substrate.
In this invention, the positioning section is formed at the accommodating section for accommodating the electro-optical panel in the case member, so that a protruding edge for positioning the electro-optical panel at an edge of the case member, which is required in a conventional device, is no longer required. Therefore, the case member can be formed thinner. In addition, since the protruding edge is not required, the heat-dissipation capability of the electro-optical panel can be increased. Further, in order to reduce optical effects resulting from scratch defects and dust, a flat transparent substrate or a transparent member, such as a small lens, a polarizer, or other such optical members may be disposed on a surface of the electro-optical panel. Here, the positioning section is disposed at the accommodating section, so that, regardless of whether or not a transparent member is accommodated, the positioning of the electro-optical panel is not affected. In addition, it is not necessary to change the case member regardless of, for example, whether or not a transparent member is used or the types of other members used, so that the same case member can be used in common with various types of products. Consequently, it is possible to flexibly and quickly respond to demands, to reduce manufacturing costs, and to easily control the manufacturing process.
It is preferable that the positioning section positions the electro-optical panel in at least the thickness direction thereof. The positioning section may be formed so as to position the electro-optical panel in a direction of extension of a surface of the panel, or to position it in both the thickness direction thereof and the direction of extension of the surface of the panel. The electro-optical panel is not limited to a liquid crystal panel described later, so that, for example, an EL (electro-luminescence) panel or an organic EL panel may also be used.
In the present invention, it is preferable that the open section at the opposing substrate side and the open section at the element substrate side in the case member be capable of receiving corresponding transparent members.
In this case, it is not necessary to form positioning sections for positioning the electro-optical panel at the pair of open sections at the sides of the accommodating section including the positioning section, making it possible to form the transparent substrates and other parts which are accommodated in the pair of open sections to the same dimensions, thereby reducing manufacturing costs and facilitating parts control.
In the electro-optical device of the present invention, a light-shielding member may be disposed on at least one of the opposing substrate and the element substrate. The light-shielding member is provided outside the display area of the electro-optical panel.
According to this structure, when, in particular, a transparent member is not used, the light-shielding section is disposed at the outer peripheral portion of the electro-optical panel, so that light trying to enter from the outer periphery of the electro-optical panel is blocked, making it possible to prevent reduced contrast and malfunctioning of the electro-optical panel caused by the entrance of light.
The light-shielding member may be formed to include a light-transmissive section at an area corresponding to the display section. In such a structure, the display surface includes a transparent section, making it possible to prevent dust from sticking onto and scratches from being formed on the display surface.
A stepped section may be formed at the open section at the element substrate side in the case member.
According to this structure, when the transparent member is joined to the element substrate, the element substrate and the transparent member can be positioned by the positioning section and the stepped section.
A gap may be formed between the inside surface of the case which may consist of positioning section and the stepped section and a periphery of a portion where the element substrate and the transparent member are joined together.
According to this structure, even when any adhesive overflows from the portion where the element substrate and the transparent member are joined together, the overflowing adhesive can be accumulated in the gap, so that the adhesive is prevented from flowing out the case member.
According to the present invention, there is provided an electro-optical device which may consist of:
an electro-optical panel including an opposing substrate and an element substrate having a larger area than the opposing substrate; and
a case member including an open section at the opposing substrate side, another open section at the element substrate side, and an opening for inserting the electro-optical panel in a direction perpendicular to the open sections,
wherein, between the open section at the opposing substrate side and the open section at the element substrate side, the case member includes a positioning section which accommodates the opposing substrate and contacts an edge of the element substrate.
According to this structure, regardless of the sizes of the open sections at the opposing substrate side and the element substrate side, it is possible to accommodate the electro-optical panel from the opening.
According to the present invention, there is provided an electro-optical device which may consist of:
an electro-optical panel including an opposing substrate, an element substrate having a larger area than the opposing substrate, and a transparent member which is joined to the opposing substrate and which has a larger area than the opposing substrate; and
a case member including an open section at the opposing substrate side and another open section at the element substrate side,
wherein, between the open section at the opposing substrate side and the open section at the element substrate side, the case member includes a protruding section sandwiched by an edge of the element substrate and an edge of the transparent member.
According to this structure, it is possible to position the electro-optical panel by the protruding section.
According to the present invention, there is provided an electro-optical device which may consist of:
an electro-optical panel including an opposing substrate, an element substrate, and a transparent member which is joined to the opposing substrate and which has a smaller area than the opposing substrate; and
a case member including an open section at the opposing substrate side and another open section at the element substrate side,
wherein, between the open section at the opposing substrate side and the open section at the element substrate side, the case member includes a positioning section which contacts an edge of the opposing substrate.
According to this structure, when the transparent member having a smaller area than the opposing substrate is joined to the opposing substrate, it is possible to position the electro-optical panel using the opposing substrate.
According to the present invention, there is provided an electro-optical device comprising:
an electro-optical panel including an opposing substrate, an element substrate, and a transparent member which is joined to at least one of the opposing substrate and the element substrate and which is at least partly formed of monocrystalline sapphire; and
a case member including an open section at the opposing substrate side and another open section at the element substrate side,
wherein the case member includes a positioning section which accommodates the electro-optical panel and contacts an edge of the electro-optical panel.
According to this structure, by forming at least a portion of the transparent member with monocrystalline sapphire having a very high thermal transmittance ratio, which is at least 20 to 30 times greater than those of various types of glass, the thermal transmittance ratio of the transparent substrate is increased, thereby increasing the heat-dissipation capability of the electro-optical panel and reducing the temperature distribution within a surface of the electro-optical panel. Therefore, it is possible to reduce deterioration caused by overheating and temperature distribution, and limit increases in, for example, energy consumption and noise by increased cooling of a cooling device. Compared to the hardness of various types of glass, the Vickers hardness of monocrystalline sapphire is two to four times greater, so that the outer side portions of the transparent substrate can be made harder. Therefore, it is possible to prevent the surface of the transparent substrate from getting scratched, and the transparent substrate from breaking and cracking. In addition, compared to, for example, glass, monocrystalline sapphire has a higher refractive index, so that even when the transparent substrate is formed thin, a defocusing effect can be obtained.
It is desirable that a projection display device is constructed so as to include any one of the above-described electro-optical device of the present invention as an image-forming, device. By virtue of this structure, an electro-optical device with good heat-dissipation capability can be realized, and, for example, the strength of the cooling fan can be reduced, so that a compact projection display device in which electrical power consumption is reduced can be constructed.